Consumer Reports encourages companies to offer the technology as a standard feature, without requiring consumers to pay thousands more for a higher option package.

“When we purchased our latest test car, we were assured automatic emergency braking would be enabled by the end of 2016,” says Jake Fisher, director of Consumer Reports’ Auto Test Center in Colchester, Conn. “We’ve been waiting for this important safety feature, which is standard equipment on much cheaper cars.” (Read "Updated Tesla Model S 60D Adds Features and Promises.")

The Tesla Model S loses two points in the ratings, dropping to a score of 85, from 87. The original higher score was based on the AEB system in the earlier version of the Model S. The new lower score moves the ranking from the top spot in the ultraluxury car category to third behind the Lexus LS and BMW 7 Series, among the seven cars rated. (See our luxury car ratings.)

The Tesla Model S.Tesla

For the Tesla Model X, the score drops to 56 from 58, moving it to near the bottom of the luxury midsized SUV category.

Once Tesla deploys AEB to all owners and starts selling all new vehicles with the feature activated, Consumer Reports will re-evaluate the overall scores.

In an e-mailed statement, Tesla said the company expects AEB to be included in a software update this Thursday, April 27. Updates happen over the air and often take days, even a week or two, to take effect for all vehicles.

“Automatic Emergency Braking and other safety features are a top priority, and we plan to introduce them as soon as they’re ready,” Tesla said in the statement. “We believe it would be morally wrong and counterproductive to our goal of improving consumer safety to release features before they’re ready, and we believe our customers appreciate that.”

Tesla declined to answer a question about any potential compensation for owners who have driven their vehicles for up to six months without the benefit of advanced safety functions and convenience features they may have expected much sooner.

Responding to a lawsuit filed last week seeking compensation for the slow rollout of AEB and other technology, Tesla called the claims “inaccurate and sensationalistic.” Tesla accused the plaintiffs of spreading “exactly the kind of misinformation that threatens to harm consumer safety.”

Tesla's assembly line.Benjamin Zhang/Business Insider

When Consumer Reports purchased its brand-new Model S 60D on Dec. 12, the AEB feature was not operational like it was in the previous version. The vehicle was equipped with second-generation Autopilot hardware. CR engineers expected the standard AEB feature to be turned on in just a few weeks, along with other optional safety features. That didn't happen.

In emails and letters over the past several months, Tesla repeated pledges to owners that the software would soon be deployed.

The wait for Tesla customers began Oct. 19, when CEO Elon Musk announcedthat the automaker would be equipping all future models with new cameras and sensors that would eventually enable self-driving capability—after the development of supporting software and approval by regulators.

The downside to the new hardware, the company disclosed at the time, was that some basic safety features wouldn’t be immediately available because software for those systems would have to be rewritten and validated.

Despite that explanation, Tesla still was selling premium luxury cars without basic safety features that come standard on far less expensive vehicles, such as the $20,000 Toyota Corolla.

A prospective Tesla buyer late last year might have considered a short delay a minor inconvenience. But now someone who bought a Tesla with advanced hardware after October has been driving without the safety feature for roughly half a year.

Tesla has said repeatedly that AEB is a top priority. The company has said it’s introducing features as soon as they're ready. But Tesla’s deployment of the safety feature has been consistently behind schedule.

Musk said Nov. 26 on Twitter that new software would be out in “about three weeks,” with monthly updates after that. He was responding to a new Model S owner upset about “all these missing features.”

Consumer Reports has received four software updates to its Model S, but none has included AEB.

Consumer Reports questioned Tesla in January about AEB as part of planning for the magazine's Annual Auto Issue, which focuses on vehicle testing and ratings. Tesla gave reassurances then that AEB would be launched soon. The company further assured CR testers for the review of the Model S 60D in February that the update was weeks away. When the review was published March 17, the new AEB still had not been launched.

Read the original article on Consumer Reports. Consumer Reports is an independent, nonprofit organization that works side by side with consumers to create a fairer, safer, and healthier world. CR does not endorse products or services, and does not accept advertising.